The two staffs are T shaped with the ends covered by a square of gilt brass, which is also decorated with a line on the edges. An additional length can be slid inside the staff and is fixed by means of a screw. The staffs are graduated on all four edges and numbered 1 to 3, each unit subdivided to 1/2 and to 1/4. The supplementary length is numbered from 1 to 3 with the same scale and is divided to 1/4 from [0] to 1, to 1/8 from 1 to 2, and to 1/12 from 2 to 3.
